You guys have to check this video out as well. Marble Machine 3 My summary: Holy shit!

It's a long video and pretty slow, but what a bloody amazing creation. Basically a kinetic machine made of ramps, pulleys, gears and other contraptions to move a ball bearing from the bottom of the machine to the top. And repeat this process for 24 hours powered simply by a 21lbs weight descending down a shaft. There's another weight, a counter-weight, which is directly responsible for the ball's travels. This counter weight can raise the ball 42" three times in a single drop. The counter weight can be lifted to its apex with only a 1/16" drop of the primary 21lbs weight. Damn!

Oh, everything is made by hand (using tools of course). Out of wood.

Anyway, check it out.